A Sharp Way To Enhance Cellphone Reception

Today's guest blogger is Adam P. RilfÃ¶l, a professor of physics at YÃ¿ke University, in Stockholm, Sweden. He blogs on an ingenious yet inexpensive way to avoid dropped calls.

Adam P. RilfÃ¶l

Archimedes got his big idea naked, in his bath; Alexander Fleming, while throwing out old Petrie dishes in his lab. For me, it came a few months ago while I was talking on my cellphone. I suddenly realized that when I held a pencil and the phone in the same hand, the signal improved markedly. I thought that it was strange that no one had investigated this phenomenon before. My "eureka" moment came when I realized that the key to the improved reception from the pencil only occurred when the graphics instrument was precisely the right length to resonate with the radio signal.

Photo: ANDERS FRICK

THROWBACK LOOK: The latest accessory in cellphone fashion is the humble No. 2 graphite pencil, a quirky new look showing up in major cities.

It is the graphite in the pencil that does the resonating. In Europe and most of the rest of the world, it must stretch exactly to 16.7 centimeters, corresponding to the 1800 megahertz band. In North America, it must be 15.8 cm long, for the 1900 MHz band.

I investigated the peculiarity further, first doing back-of-the-envelope calculations, then relying on software of my own design to model radio-frequency field equations. I quickly zeroed in on the problem the pencil will help to solve.

Photo: ANDERS FRICK

PENCIL PUSHER: The trick to the improved reception of proximity pencils lies in the electromagnetic properties of graphite. The simplicity of the design, though, makes a statement about the user.

Wireless signals follow many paths from their base station; and in many cases, they reach the phone out of phase, so that they cancel one another out. The phenomenon is known as multi-path fading. One of the best ways to counter it is to use several antennas.

In proximity, additional pencils increase the gain, but the margin of improvement soon declines sharply. My students and I could hardly detect any significant improvement after adding a fifth pencil.

I had some of my students perform field tests using pens, knitting needles, cutlery, and other commonly available implements. Those of the proper length sometimes worked as well or even better than the pencils, but few will probably care to use them. Most people, in my opinion, would prefer not to walk around with a fork and knife so close to their ear (even though it would be quite convenient at dinner time).

Photo: ANDERS FRICK

EASE OF ASSEMBLY: Proximity-pencil reception can be achieved with items found in any stationery shop, assembly is quick and easy, and variations on the technique offer a range of customization options.

My colleagues and I are now trying to apply our pencil solution to other radio-frequency receivers, notably those tuned for the WiFi signals used to connect wirelessly to the Internet. Here, too, the classic No. 2 pencil should be all that is needed to improve connectivity.

Recently, a reporter asked me what I thought was the best thing about using pencils to boost your cellphone reception. Sensing a chance to inject a little good-natured levity into the conversation, I replied with an air of academic seriousness, "You never have to look for one when you need to write down a number." But I don't think he could tell I was attempting to be humorous, unfortunately.

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